GB2115020A

GB2115020A - Piecing in open-end spinners

Info

Publication number: GB2115020A
Application number: GB08302075A
Authority: GB
Inventors: Kurt Lovas; Walter Mayer; Stephan Wittmann
Original assignee: Schubert und Salzer Maschinenfabrik AG; Rieter Ingolstadt GmbH
Current assignee: Rieter Ingolstadt GmbH
Priority date: 1982-01-26
Filing date: 1983-01-26
Publication date: 1983-09-01
Also published as: MY8700268A; US4644742A; SG87486G; GB2138849A; GB2138849B; HK7587A; EP0274016A2; EP0274016B2; JPH0418048B2; IN160080B; EP0084659B1; DE3202428C2; EP0084659A2; GB8302075D0; MY8700335A; CS53588A3; GB2115020B; JPH0316405B2; CS51383A3; CZ277680B6

Description

1 GB 2 115 020 A 1

SPECIFICATION

Method and apparatus for joining a thread in an open-end spinning apparatus The present invention relates to a method of joining a thread in an open-end spinning apparatus, in which the thread is delivered back to the open-end spinning apparatus by turning back a bobbin and an auxiliary pair of rollers and is subsequently drawn out of the open-end spinning apparatus again by means of a pair of draw-off rollers, as well as to an apparatus for performing this method.

In order to join a thread it is known both to raise the bobbin from the main drive roller and to retain it separate from the latter as well as to deliver the thread back to the spinning apparatus by means of an apparatus, the thread which has been delivered back being picked up from the surface of the bobbin by means of a suction apparatus and being supplied to a pair of draw-off rollers (U.K. Patent A306,232). At the pair of auxiliary rollers the thread is brought to a specific length, whereupon a predetermined thread length is delivered to the open-end spinning apparatus by further return delivery. After return delivery has occurred the thread is firstly drawn out of the open-end spinning apparatus by means of the auxiliary pair of rollers until the thread is inserted in the pair of draw-off rollers after a desired bobbin speed has been reached.

In the case of this known method, during the thread joining process there is only a short period of time between the return delivery of the thread into the spinning rotor and the beginning of the thread draw-off process from the spinning rotor. If this period of time is exceeded the thread is overtwisted such that a break in the thread occurs. On the other hand, during the short interval of time for which the thread end remains in the spinning rotor during the thread joining phase, the twist is not transmitted to a great extent to the fibre ring, such that when a thread draw-off process begins very suddenly, as is the case with the known apparatus, there is also the danger of breaks in the thread.

It is also known, to unwind the thread manually from the bobbin and guide it back into the spinning rotor. Subsequently the bobbin is again brought into connection with its drive roller such that the thread is drawn off from the bobbin (U.K. Patent 1,155,313) until it is grasped by the traversing thread guide and is brought into the region of a catching groove on the pressure roller of the pair of draw-off rollers, which brings the thread into the clamping region of this pair of rollers. In the case of this apparatus the thread is 120 jerkily accelerated both at the beginning of the winding process and also when the thread is grasped by the catching groove, which may lead to breaks in the thread. Moreover, with the known apparatus it is not possible to achieve a specific beginning of the draw-off process, since, in the case of the known prior art, the bobbin is supported on the drive device and the varying mass of the bobbin when the thread join is drawn off causes a varying slip of the bobbin. Tolerances in the shock absorbers and load equalizing devices for the bobbin arms furthermore cause varying thread joining conditions at the various spinning stations of a machine, which renders control of the thread joining process more difficult.

It is therefore an object of the invention to provide a method and apparatus which avoid these disadvantages and ensure a definite beginning of the thread draw- off process when the thread is joined even when there is a plurality of spinning stations.

In order to achieve this object it is provided in accordance with the invention that, after termination of return delivery, the thread is released from the auxiliary pair of rollers, and until the beginning of the normal spinning draw-off process, is subjected to an auxiliary draw-off process at a greater distance from the open-end spinning apparatus than this spinning draw-off process. As a result of the releasing of the thread by the auxiliary pair of rollers, as soon as the latter has completed its task of returning the thread to the open-end spinning apparatus, the twist occurring in the yarn in the draw-off tube as a result of the rotation of the spinning rotor, can be distributed over a relatively great thread length, such that twist does not pass into the spinning rotor to such a great extent.

As a result thereof, in contrast to the known method, by means of an auxiliary pair of rollers, more time is available during the spinning of a thread join as retention time of the thread in the spinning rotor. This longer amount of time available also enables the thread draw-off process to be started more smoothly. As a result of the fact that the thread is subject to an auxiliary drawoff process at a greater distance than is the case with a normal spinning draw-off process, an even greater length is available for taking up the twists. As a result of these two measures the number of thread breaks during thread joining is reduced and the resistance to tearing in the thread join is substantially increased, since in this way a certain adaptation of the thread draw-off run-up curve to the run-up curve of the thread supply effective in the spinning rotor occurs.

According to an advantageous construction, the auxiliary draw-off process occurs solely by means of the bobbin. in this way the smoother beginning of the thread draw-off process may be caused by a certain, although defined, slip of the bobbin. This slip is also advantageous since, during thread joining, the fibre delivery to the spinning rotor---or to another open-end spinning element-does not begin suddenly, but gradually. After a short time, which is sufficient for the bobbin to reach its full speed, the thread is transferred to the pair of draw-off rollers. Since the thread at this time has already been drawn off at full speed from the open-end spinning apparatus, there are also no jumps in the speed in 2 GB 2 115 020 A 2 this connection, such that there is also no danger of breaks in the thread at this time.

However, it is not absolutely necessary for the draw-off of the thread join to occur by means of the bobbin; it is certainly possible, and, in connection with further operating steps which are to be performed in connection with the thread joining, it is often extremely suitable if the auxiliary draw-off process occurs independently of the bobbin.

Advantageously the auxiliary draw-off process is maintained in an essentially constant relation with respect to the run-up curve of the fibre feed effective in the open-end spinning apparatus. As a result of this, at the moment of the beginning of 80 the thread draw-off process, less fibrous material is required in the open-end spinning apparatus such that the excess amount of fibre in the open end spinning station which would otherwise lead to a thick point in the thread thickness, may be avoided, whereas at the same time, as a result of the increasing rotation transmission in the open end spinning apparatus, the resistance of the yarn with respect to the thread joins produced hitherto in the usual manner does not decrease.

In order that more time is available for the beginning of the thread join draw-off process, such that the tolerances therefor may be selected such that they are even greater without impairing reliability of the thread joining, it is provided that 95 the return delivery time is reduced to a minimum.

In accordance with the invention this is achieved in that, before the return delivery of the thread, a reserve thread is formed via a throw-off member and the thread end to be delivered to the open end spinning apparatus is brought to a defined length, in that the return delivery of the thread end by means of the auxiliary pair of rollers only occurs into a readiness position inside the open end spinning apparatus and in that after the thread has been released by the auxiliary pair of rollers the return delivery of the thread join occurs as a result of the thread being thrown off by the throw-off member. As a result thereof it is not only achieved that the time tolerances for the beginning of the thread-join draw-off process are greater, but an extensive self-control of the thread-joining process also results since the imparting of twist to the thread is automatically adapted to the diameters of the yarn, to the extension properties thereof, etc. This automatic adaptation of the thread-joining process to the properties of the yarn also enables the time tolerances for the beginning of the thread-join draw-off to be selected such that they are larger.

If the spinning member, e.g. a spinning rotor, is interchangeable such that collecting surfaces with different diameters may be used, it is necessary to adapt the return delivery path thereto. In order to obtain constant thread-joining conditions, the actual return delivery of the thread join should always occur under constant conditions.

Therefore the adaptation to the different diameters according to the invention does not occur by means of the throw-off member but by 130 means of the auxiliary pair of rollers. According to a further feature of the invention this occurs in that the readiness position inside the open- end spinning apparatus is selected such that the path of the thread-join return delivery by means of the throw-off of the thread is always the same size, irrespective of the diameter of the spinning member in each case.

Taking as a starting point an apparatus for joining a thread in an open-end spinning apparatus, with an auxiliary pair of rollers for the taking up, return delivery and releasing of the thread at the open-end spinning apparatus, with a pair of draw-off rollers for drawing off the thread during the normal spinning process, an auxiliary draw-off apparatus is provided for performing the abovementioned method in accordance with the invention and is arranged at a greater distance from the open-end spinning apparatus than the pair of draw-off rollers. The thread join draw-off process may be performed in the desired manner by means of this auxiliary draw-off apparatus. Since the auxiliary draw-off apparatus is arranged at a greater distance from the openend spinning apparatus than the auxiliary pair of rollers the twist occurring in the thread joining phase is distributed over a greater length of the thread such that the danger of over-twisting the thread end of the thread join in the spinning rotor is reduced. As a result of this it is rendered possible to operate at essentially higher rotor speeds with respect to conventional thread joining methods. This means that it is generally not necessary to maintain the spinning rotor at a low speed for the thread joining process or to monitor its speed, but allows the thread joining process to occur at the high production rotor speeds which are usual today.

In the case of a bobbin device comprising the bobbin arm for taking up a bobbin, with a main drive roller for driving the bobbin and with a device for raising the bobbin from the main drive roller and for driving the bobbin, this device comprising a pivot arm, a roller which may be driven in both directions and a controllable pivot drive, for the pivot arm, operating against the effect of a resilient element, it may be provided in accordance with the invention that the auxiliary drawoff apparatus is formed by the bobbin device, the device for raising and driving the bobbin consisting of a bobbin lifting device for forming a defined distance between the bobbin and the main drive roller and of an auxiliary bobbin drive which may be caused to act on the side, of the bobbin, remote from the main drive roller by the action of the resilient element.

Immediately when a thread break occurs the bobbin is raised by the bobbin lifting device from the main drive roller. This may occur so rapidly that the end of the broken thread no longer reaches the bobbin at all and hangs down freely from the bobbin. Thus it is particularly easy to take up the thread for return delivery. However, even when the thread passes onto the bobbin it may easily be taken up here during subsequent ko 1 3 i t 3 GB 2 115 020 A 3, winding back of the bobbin since the thread is prevented from being firmly wound into the bobbin by the rapid stopping of the bobbin. The bobbin lifting device is constructed such that a defined distance is formed between the bobbin and the main drive roller, such that the current radius of the bobbin is effective on the operating position of the auxiliary bobbin drive which cooperates with the side of the bobbin remote from the main drive roller. In this manner various positions of the pivot arm of the auxiliary bobbin drive are obtained according to the size of the bobbin when the latter is driven.

The pivot drive is constructed such that it causes the roller to be lifted from the bobbin, whereas when the pivot arm is released by the pivot drive the resilient element causes the roller to lie against the bobbin. Since the position in which the roller lies against the bobbin differs depending upon the radius of the bobbin, the resilient element is prestressed to varying degrees during the operation of the roller, such that the roller also lies against the bobbin with varying degrees of force. By suitable selection of the characteristic data of the resilient element, e.g. by 90 constructing the resilient element as a spring, it may be achieved by a corresponding selection of the spring constants, dimensions and pre stressing of the spring, that slip which normally varies in the case of bobbins of different sizes is 95 avoided, such that slip which is essentially always the same, and thus thread joining conditions which are always the same, are obtained irrespective of the bobbin diameter.

In order to achieve a greater operating area for 100 the roller it is advantageously provided that the bobbin lifting device is constructed such that it forms a defined distance between the peripheral faces of the bobbin and the main drive roller. In this manner the full bobbin diameter affects the 105 pre-stressing of the resilient element, which substantially facilitates compensation of the differing bobbin mass by the differing contact pressure of the roller.

The defined distance between the peripheral faces of the bobbin and the main drive roller may be achieved in different ways. Advantageously the bobbin lifting device comprises a lifting element cooperating with the side, of the bobbin, facing the main drive roller, a support device which 115 ensures the defined distance between the peripheral faces of the bobbin and the main drive roller and cooperates with a bobbin arm, being associated with the bobbin lifting device. Since the lifting element of the bobbin lifting device cooperates with the side, of the bobbin, facing the main drive roller, as a result thereof the defined distance between the peripheral faces of the bobbin and the main drive roller may be obtained in a particularly simple manner. Thus monitoring devices for checking this distance, for example light barriers susceptible to fly are not necessary. In order that the bobbin may be rotated for thread joining the support element cooperating with a bobbin arm is provided in accordance with the invention and ensures the defined distance between the peripheral faces of the bobbin and the main drive roller, even if the lifting element releases the bobbin again.

It is particularly advantageous in the case of an open-end spinning machine with a plurality of open-end spinning devices if only the bobbin lifting device is arranged so as to be stationary for each spinning station, whereas the support device and the auxiliary bobbin drive are arranged on a servicing apparatus movable along the open-end spinning devices. In this way a bobbin apparatus which is not complicated and is suitable for thread joining according to the invention may be provided.

In order to avoid non-contact monitoring devices for the position of the support device for the bobbin, since they are susceptible to disorders owing to fly which may possibly occur, it is advantageously provided that the support device comprises a drive lever which may be pivoted by a controllable drive and a support lever which is disposed on the drive lever, may be pivoted between two end positions, is acted upon by a resilient element in the direction towards the bobbin and may thereby be brought into its first end position and, by running up on one of the two bobbin arms, may be brought into its second end position, with which a switching apparatus for terminating the pivoting movement of the drive lever is associated. In this way the switching apparatus is mechanically actuated. Moreover, by means of the above-mentioned apparatus according to the invention it is achieved that, inspite of different positions of the bobbin arms, the latter are always supported by the support device such that the defined distance between the peripheral faces of the bobbin and the main drive roller is ensured, such that the lifting element may be withdrawn and the supporting function may be left to the support device. According to a preferred embodiment of the subject matter of the invention the controllable drive for the drive lever is constructed as an electric motor and the switching apparatus is constructed as an electric switch which is disposed on the drive lever and interrupts the supply of current to the motor when actuated by the support lever. Advantageously the end positions of the support lever are determined by two stops mounted on the drive lever.

The resilient element associated with the pivot arm may be constructed in different ways, but in accordance with the invention, in order to obtain a compact construction of the auxiliary bobbin drive it is preferable for the resilient element associated with the pivot arm to be constructed as a torsion spring.

In order to be able to control various elements operating during the thread joining process from the same drive, according to a further feature of the invention it is provided that the pivot drive for the pivot arm comprises a rotatable cam disc and an adjustable intermediate lever system between the cam disc and the pivot arm. This intermediate :7_ ' 4 GB 2 115 020 A 4 lever system enables the pivot arm to be adjusted in a particularly simple manner.

In order to avoid the roller of the auxiliary bobbin drive being pressed with great force into the bobbin even in the case of a relatively large bobbin diameter, it may be further provided in accordance with the invention that the roller bears a cover consisting of a soft material, preferably soft rubber.

By means of the apparatus according to the 75 invention good quality thread joins are obtained.

Inspite of this it can be advantageous for some purposes to provide a knot or some other thread connection instead of the thread join. For this purpose it is advantageous to draw-off the thread independently of the bobbin from the open-end spinning apparatus. For this purpose, according to a further feature of the invention, it is provided that the auxiliary draw-off apparatus is formed by a second auxiliary pair of draw-off rollers which may be caused to act on the side, of the pair of draw-off rollers, facing away from the open-end spinning apparatus. Although in principle it is possible to use generally an auxiliary pair of draw- off rollers of this type for performing the thread join draw-off operation, such an apparatus-as mentioned-is particularly advantageous in connection with a thread connecting apparatus replacing the thread join, for which reason in a further embodiment of the subject matter of the invention a thread connecting apparatus between the pair of draw-off rollers and the second pair of auxiliary draw-off rollers may be brought into the thread path.

In order to be able to increase further the time 100 tolerances available for the beginning of the thread j oin draw-off process, the return delivery occursin two stages. For this purpose, in accordance with the invention, a thread cutting apparatus and a return delivery measuring 105 apparatus are associated with the auxiliary pair of rollers, whereas a thread throw-off member is arranged between the pair of draw-off rollers and the bobbin and deflects the thread. The thread cutting apparatus and the return delivery 1 measuring apparatus have the task of bringing the thread to a defined length and into a predetermined readiness position whereas the throw-off member enables the thread to come into contact with the fibres delivered to the open- 115 end spinning apparatus. In order to provide constant thread join return deliveries by means of the throw-off member and thus also constant thread joining conditions even when the spinning member may be exchanged for a spinning member whose fibre collecting surface has a different diameter, according to a further feature of the invention it is provided that the return delivery measuring device may be adjusted in dependence upon the diameter of the spinning member selected in each case.

The subject matter of the application provides the conditions such that thread joins may be reliably spun even at high rotor speeds such that a precise adaptation with respect to time of the joining process to the run-up curve of the spinning rotor is not necessary. As a result of this a substantial simplification of the control is achieved which follows great time tolerances and is thus easily controllable.

Further advantages and details of the invention will be described with reference to the following description and an embodiment illustrated in drawings, in which:

Figure 1 is the subject matter of the invention in a schematic side view; Figure 2 is a variation of a detail of the apparatus illustrated in figure 1 in plan view; and Figures 3 and 4 show a further variation of the subject matter of the invention in two different operating phases in schematic side view.

Firstly, the apparatus and the method will be described with reference to figure 1. In this figure the essential parts of a spinning machine 1 operating according to the open-end spinning method are shown, insofar as they are necessary for comprehension of the explanation. In practice these parts are distributed on the spinning machine 1 and a servicing apparatus 2 which may travel along the spinning machine 1, however it is also possible to provide all the elements shown on the spinning machine 1 itself and to dispense with the servicing apparatus 2, in particular with test machines with one or only a few spinning stations.

The illustrated spinning machine 1 comprises a plurality of spinning stations, of which figure 1, however, only illustrates one. An open-end spinning apparatus with a spinning element disposed in a housing 10, a pair of draw-off rollers 13 and a bobbin apparatus 30 are provided at each spinning station. In the illustrated embodiment a spinning rotor 11, for example, acts as the spinning element and produces a thread 3 which, after the binding of fibres which are delivered to the spinning element in the usual manner by means of a fibre delivery apparatus and a releasing apparatus-for example in the form of a releasing roller-is drawn off out of the housing 10 by means of the pair of draw-off rollers 13 through a draw-off tube 12. A thread monitor 36 is disposed in the thread path between the housing 10 and the pair of draw-off rollers 13.

In order to wind on the thread 3 the spinning machine 1 comprises a bobbin apparatus 30 which essentially comprises a main drive roller 31 for driving the bobbin 33 which is interchangeably taken up by two pivotable bobbin arms 32. The bobbin arms 32 may be pivoted about a shaft 34.

In order to equalize the thread tension which varies during traversing of the thread, a thread tension equalizing member 14 is arranged in a known manner in the thread path between the pair of draw-off rollers 13 and the bobbin 33.

At the spinning machine 1 there is further provided for each spinning station a lifting element 40 which forms part of the bobbin lifting device 4 and raises the bobbin 33 by a certain a GB 2 115 020 A 5 value a from the main drive roller 31 by insertion between the main drive roller 31 and the bobbin 33, such that a distance a defined by the thickness of the lifting element 4 is formed between the peripheral faces of the bobbin 33 and the main drive roller 31.

A suction tube 20 is disposed on the servicing apparatus 2 and may be brought to the lower side of the bobbin 33 raised from the main drive roller 31 in order to be able to take up the end of a torn thread 3 there. The suction tube 20 has a bent shape and, on its side facing the spinning machine 1, has an elongate slot (not shown) such that as an increasing amount of the thread 3 enters the suction tube 20 the thread 3 may partially leave the latter again in the form of a chord. The servicing apparatus 2 further bears an auxiliary pair of rollers 21 which is borne by a 20 lever 23 which may be pivoted about a shaft 22 in 85 such a way that the auxiliary pair of rollers 21 may grasp the chord-like thread 3 arranged with respect to the suction tube 20 and deliver it to the drawoff tube 12. 25 There is further disposed on the servicing apparatus 2 an auxiliary bobbin drive 5 which comprises a pivot arm 50, which is pivotably mounted on a shaft 51 and bears at its free end a roller 52 which may be optionally driven in a manner not shown by a drive (not shown) in one 95 direction or the other. The roller 52 is surrounded by a cover 53 consisting of soft rubber or some other soft material.

There is further arranged on the servicing apparatus 2 a pivot drive 6 for the pivot arm 50 100 which, in the embodiment shown, comprises a camshaft 61 which is driven by a motor 60 and on which a cam disc 62 is arranged. On a shaft 63 borne by the servicing apparatus 2 a two-armed lever 64 is pivotably mounted, at one end of which the cam disc 62 may engage and to the other end of which an adjustment member 65 is connected. This adjustment member 65, the free end of which is connected to the pivot arm 50, consists in the embodiment shown of two bolts 110 66 and 67 comprising oppositely directed threads and onto which a threaded sleeve 68 with oppositely directed threads is screwed, such that by rotating the threaded sleeve 68 the distance between the lever 64 and the pivot arm 50 may 115 be altered. In this manner it is possible to adjust the lever 64 accurately with respect to the pivot arm 50. In a corresponding position the cam disc 62 causes the roller 52 to lift from the bobbin 33, whilst a tension spring 7 engaging at the pivot 120 arm 50 causes the pivot arm 50 to be supported on the bobbin 33 when the lever 64 is released by the cam disc 62.

An additional arm 35 is mounted on the bobbin arm 32 with which arm 35 a support device 8 may cooperate. In the illustrated embodiment the support device 8 consists essentially of a pivotably mounted drive lever 80, at the free end of which a support lever 81 is hinged. This two- armed support lever 81 may be moved between two steps 82, and 83, mounted on the drive lever 80, and is acted upon by means of a resilient element, which is formed as a pressure spring 84 and one end of which is supported on the drive lever 80 and the other end of which is supported on the support lever 81, such that the support lever 81 normally is supported on the stop 82. A switch 85 is provided at the drive lever 80 such that the support lever 81 actuates this switch 85 when lying against the stop 83, without being supported on the switch housing. The switch 85 is electrically connected to a motor 86 which acts as a pivot drive for the drive lever 80 and secures the drive lever 80 in its current position when being immobilised. The motor 86 is connected to a control device 9 which is also connected to the motor 60.

The apparatus described above operates as follows:

When a thread brake occurs it triggers, via the thread monitor 36, the termination of the fibre supply to the spinning rotor 11 and the raising of the bobbin 33 from the main drive roller 3 1, in that the lifting element 40, forming the essential component of the bobbin lifting device4, is pushed between the bobbin 33 and the main drive roller 3 1. Thus the winding of the thread 3 onto the bobbin 33 is interrupted extremely rapidly and depending on the winding-on speed it is often even before the thread end has reached the bobbin 33. As a result of pushing the lifting element 40 in between the main drive roller 31 and the bobbin 33 the bobbin lifting device 4 forms a precisely defined distance a between the peripheral faces of the bobbin 33 and the main drive roller 3 1, this distance a corresponding to the thickness of the lifting element 40 between the bobbin 33 and the main drive roller 31.

As a result of the releasing roller (not shown), which also continues to run after the fibre delivery device has stopped, the fibre tuft projecting into the operating area of the separation roller is trimmed off and delivered to the spinning rotor 11 together with the fibres in the fittings of the separation roller.

In a known manner a signal is triggered from the above-mentioned thread monitor 36, which signal calls up the servicing apparatus 2 or causes the continuously circulating servicing apparatus 2 to stop at the faulty spinning station in order to remove the thread break.

When the servicing apparatus 2 has assumed its operating position at the spinning station in question a rotor cleaning apparatus (not shown) is temporarily switched on from the control device 9, as a result of which the fibres in the spinning rotor 11 are removed therefrom in a manner known per se. Furthermore, in a manner which is not shown, from the servicing apparatus 2, the pressure roller of the pair of draw-off rollers 13 is raised from the driven roller. Moreover, the drive lever 80 with the support lever 81 is pivoted upward by means of the motor 86. During this movement the support lever 81 resting on the stop 82 comesto Heon the arm 35 of the bobbin 6 GB 2 115 020 A 6 arm 32. As a result thereof the support lever 81 is pivoted relative to the drive lever 80 against the action of the pressure spring 84 until it lies against the stop 83. In this position the support lever 81 actuates the switch 85 which is thereby opened and thus interrupts the current supply to the motor 86. The lifting movement of the drive lever 80 is thus ended and this lever is fixed in its current position. The control device 9 now causes the lifting element 40 to be withdrawn such that it releases the bobbin 33. This may occur as a result of the servicing apparatus 2 acting mechanically upon the lifting element 40 or by actuating an electrical element (not shown) which causes this retracting action. In spite of the withdrawal of the lifting element 40, the bobbin 33 remains in its current position since it is supported by the support lever 8 1.

After the bobbin 33 has been released by the lifting element 40 the control device 9, in a manner not shown, causes the suction tube 20 to be brought into the thread take-up position. In this position the suction tube 20 is at the lower side of the bobbin 33, such that the distance between the suction tube 20 and the bobbin 33 is essentially always the same, irrespective of the diameter of the bobbin. Moreover, the control device 9 switches on the motor 60 which causes the camshaft 61 to rotate. The cam disc 62 thus releases the lever 64 such that, as a result of the effect of the tension spring 7 on the pivot arm 50, the roller 52 is brought to rest on the bobbin 33. Depending on the size of the bobbin 33 the tensioned spring 7 in this connection is tensioned to a greater or lesser extent such that in the case of a relatively large bobbin diameter the contact pressure of the roller 52 on the bobbin 33 is greater than is the case with a smaller bobbin. If the roller 52 is thus now driven via drive means (not shown) for the return delivery of the thread 3, this differing contact pressure causes the mass inertia to be compensated and avoids differing slip which would otherwise occur owing to the differing masses of the bobbin 33.

During the winding back of the bobbin 33, the thread 3, which as a result of the rapid stopping of the bobbin 33 by means of the lifting element 40 only lies loosely on the periphery of the bobbin, is drawn into the suction tube 20 and partially emerges from the suction tube 20 again in the form of a chord during the course of the suction process as a result of the bent shape of the suction tube 20. After a sufficient length of thread has passed into the suction tube 20 the return delivery of the thread 3 is interrupted by means of the control device 9 and the suction tube 20 is brought into its position shown in broken lines. Subsequently the auxiliary pair of rollers 21 is pivoted out of a rest position about the shaft 22, this auxiliary pair of rollers 21 passing through the path of the thread 3 entering the slot of the suction tube 20. By usual means which are not shown the thread is separated on the side, of the auxiliary pair of rollers 21, facing away from the bobbin 33 and the auxiliary pair of rollers is pivoted in front of the mouth of the draw-off tube 12. In the meantime, the spinning rotor 11 or another open-end spinning element has been caused to rotate and the fibre supply to the fibre collecting surface has again been switched on. In a suitable temporal adaptation thereto the thread 3 is again delivered back by rotating the bobbin 33 and the auxiliary pair of rollers 21 until the thread reaches the fibre collecting surface of the spinning rotor 11 or another open-end spinning element, whereupon the clamping action of the auxiliary pair of rollers 21 is discontinued, for example by raising the roller disposed further from the shaft 22 away from the roller disposed near the shaft 22. As a result of this the thread 3 is released from the auxiliary pair of rollers 2 1. The auxiliary pair of rollers 21 now returns to its rest position. After the release of the thread 3 by the auxiliary pair of rollers 21 the roller 52 is driven in the reverse direction such that the thread 3 is drawn out of the spinning rotor 11. The thread 3 is thus drawn out of the spinning rotor 11 exclusively by the bobbin 33 in this thread joining phase.

As illustrated, the drive of the fibre delivery apparatus is switched on at a moment which is adapted to the return delivery and renewed drawing-off of the thread 3. Since firstly the previously emptied fittings of the separation roller have to be filled again until the full fibre flow can pass into the spinning rotor 11, the fibre delivery gradually becomes effective with respect to the spinning rotor 11.

As the fibre delivery thus becomes effective the thread draw-off process should also start 11 gradually- in order to ensure a thread join with high resistance and, on the other hand, to avoid an excessively great jump in the thread tension and thus thread breaks. The roller 52 is thus accelerated in a relation adapted to the becoming effective of the fibre supply to the spinning rotor 11 to the normal bobbin speed, the unavoidable slip of the bobbin 33 being taken into consideration in the acceleration of the roller 52. As mentioned above the slip is maintained independent of the bobbin diameter in each case by selecting a corresponding spring constant, length and tension of the spring 7 in such a manner that it has no distorting effect, or only within tolerable limits, on the thread draw-off speed. When the bobbin 33 has reached the full bobbin speed the bobbin 33 is lowered onto the main drive roller 31 by pivoting the drive lever 80 and the roller 52 is raised from the bobbin 33 by the effect of the cam disc 62 on the lever 64. Furthermore, the pressure roller of the pair of draw-off rollers 13 is released from the servicing apparatus 2. Thus if the thread monitor 36 has not displayed a failure of the removal of the thread break, the thread draw-off process and the winding of the thread 3 onto the bobbin 33 occur again by means of the spinning machine 1 itself independently of the servicing apparatus 2. The removal of the thread break whose entire operating steps are controlled by the a A 1 7 GB 2 115 020 A 7 control device 9 of the servicing apparatus 2, is therefore concluded.

The method described is not limited to the embodiment illustrated. The apparatus may also be modified within the scope of technical equivalents or other combinations of features.

As mentioned, a thread separation apparatus is associated with the auxiliary pair of rollers 21 in the usual manner and brings the thread 3 to a particular length. Moreover, in a known manner a return delivery measuring apparatus is associated with the auxiliary pair of rollers 21 and determines the number of rotations of the auxiliary pair of rollers 21 and thus the quantity of the thread 3 delivered back.

As is shown in figure 1 in broken lines, a throw-off member 25 deflecting the thread 3 may be provided in the path of the thread between the pair of draw-off rollers 13 and the bobbin 33.

When the thread 3 is sucked up from the 85 bobbin 33 the thread 3 passes onto the throw-off member 25. When the thread 3, having been cut to length to a predetermined size, is subsequently delivered to the draw-off tube 12 by means of the auxiliary pair of rollers 2 1, the thread 3 follows a curved path. By means of the return delivery measuring device mentioned above-which is constructed as a timing member, for example, which controls the duration of the supply of current to the drive motor of the auxiliary pair of rollers 2 1 -the auxiliary pair of rollers 21 is driven at a predetermined number of rotations in the return delivery direction. As a result of this the thread end in the thread draw-off tube 12 reaches a precisely defined position which is characterized in figure 1 as position B1. In this position B1 the thread end is between the two ends of the thread draw-off tube 12, where it is held securely by the under pressure which is effective in the spinning apparatus. This position B1 is selected such that its distance along the thread draw-off path is essentially the same size as the additional thread length which results from the deflection through the draw-off member 25 in comparison with the normal thread course between the pair of draw off rollers 13 and the bobbin 33.

The auxiliary pair of rollers 21 now releases the thread 3 and may thus be pivoted away out of the region of the mouth of the draw-off tube 12. For joining a thread the throw-off member 25 now throws off the thread 3, the end of which reaches from the readiness position B1 into the region of the fibre collecting surface of the spinning rotor 11 selected as an example, where it binds the fibres which have been fed in in the meantime.

The drawing off of the thread join by means of the bobbin 33 now begins in time with the throwing off of the thread by the throw-off member 25.

As mentioned, the released thread length has essentially the same length as the distance of the readiness position B1 along the thread draw-off path from the collecting surface, i.e. the collecting groove of the spinning rotor 11; in this connection, however, it should be taken into consideration with respect to the thrown off 130 reserve thread that the thread end should be able to be deposited over a certain length of the periphery in the collecting groove of the spinning rotor in order to break open and bind the fibre ring. By means of the releasing of the thread 3 both by the auxiliary pair of rollers 21 and by the throw-off member 25 the thread is delivered back to the spinning rotor 11 solely by the underpressure which is effective in the open-end spinning apparatus. This return delivery occurs at different speeds depending on the properties of the thread 3 and it has been shown that threads which are able to take up a higher twist degree before twisting off occurs in the spinning rotor 11, follow this underpressure more rapidly than threads which are not resilient and therefore are more inclined to over-twisting and twisting off. As a result of this there is a certain automatic adaptation of the thread joining process to the properties of the yarn, which increases reliability of the thread join.

In the case of open-end spinning machines in which spinning elements having collecting surfaces of different diameters may be used, it is provided that the return delivery measuring apparatus may be set in dependence upon the diameter selected in each case. If, for example, the return delivery measuring apparatus is constructed as a digitally adjustable timing relay then it is sufficient to give the time corresponding to the selected diameter as a digital value, as a result of which the operating time of the drive motor for the auxiliary pair of rollers 21 and thus also the return delivery path of the thread 3 is determined.

In figure 1 a spinning rotor 110 is shown in broken lines which has a larger diameter in comparison to the spinning rotor 11. In order that the same path of the thread join return delivery obtained by the throw-off member 25 may always be provided, the timing relay is set at a longer time which is adapted to the greater rotor diameter, such that the auxiliary pair of rollers 21 delivers the thread 3 into the readiness position B11 The actual return delivery of the thread join also occurs in this case by means of the described throw-off member 25.

Although in principal it is not necessary for the throw-off member 25 to pass into its operating position before the thread 3 is delivered back by the auxiliary pair of rollers 2 1, this saves a return delivery from the bobbin 33 which is synchronized with the build up of the reserve thread by the throw-off member 25, which synchronization is required if the throw-off member 25 does not build up the reserve length until a later moment.

As described above, it is essential for the method for the twisting during the thread joining phase to be able to be temporarily transmitted further than during the normal spinning process from the thread section, in which twisting occurs into the part, of the thread 3, from the spinning rotor 11. For this purpose it is necessary to maintain the forces, which might stop twisting, on _T 8 GB 2 115 020 A 8.

the side, of the above-mentioned thread section, facing the bobbin 33 smaller than on the side of this thread section facing the spinning rotor 11 and, as far as this is structurally possible, to move them towards the bobbin 33. This may occur in that deflection points for the thread 3 during the thread joining phase are removed or at least weakened such that they do not stop transmission of twists. This may, for example, occur in that the pair of draw-off rollers 13 or its driven rollers are pivoted away out of the thread path during the thread joining process. When the thread clamping action is discontinued by raising the pressure roller from the driven roller of the pair of draw-off rollers 13, the twist may be transmitted almost unhindered in the direction towards the bobbin, whereas the transmission of twists to the spinning rotor 11 is impeded by the deflection edge at the mouth, of the draw-off tube 12, facing the spinning rotor 11.

The auxiliary draw-off process for the threadjoining process occurs in the abovementioned embodiment exclusively by the individual driving of the bobbin 33, although it is also possible for this auxiliary draw-off process to occur independently of the bobbin 33. Thus, for example, an additional auxiliary pair of draw-off rollers 900 may be brought from the servicing apparatus 2 into the vicinity of the bobbin 33 in the thread path, for the drawing off of the thread join. It is certainly advantageous for the drawing off of the thread 3 during the thread joining phase to occur exclusively by means of the bobbin 33, since in this way no additional elements are required for the thread join draw-off, but a corresponding selection of the resilient element, for example constructed as a tension spring 7, is sufficient therefore.

In the following a variant of this type with an auxiliary pair of draw-off rollers 900 will be 105 illustrated with reference to figures 3 and 4. Since a construction of this type is particularly appropriate when it is used in connection with a thread connection apparatus 97 (for example knotting apparatus, splicing apparatus etc.), by means of which the thread connection (thread join) produced when joining a thread may be replaced by another type of thread connection, this variant will be described in connection with a thread connection apparatus 97 of this type.

The auxiliary pair of draw-off rollers 900which is provided on the side, of the pair of drawoff rollers 13, facing away from the spinning rotor 11 -is located in the embodiment illustrated, as are the various elements described hereinbelow, on the servicing apparatus 2 and may if necessary be brought into its operating position. The thread 3 is inserted in the auxiliary pair of draw-off rollers, when the latter is in the vicinity of the path of the thread sucked into the suction tube 20, by means which are usual for such purposes and are not shown. On the side, of the auxiliary pair of draw-off rollers 900, facing away from the spinning rotor 11, the mouth 91 of a thread suction apparatus 90 may be brought into the path of the thread such that it may take up the excess thread when the tension is relaxed in the thread section between the auxiliary pair of drawoff rollers 900 and the bobbin 33. A cutting apparatus 92 is associated with the mouth 91 of this thread suction apparatus 90 and may be controlled in a suitable manner. In the embodiment illustrated the cutting apparatus 92 is disposed on an arm 94 which is pivotable about a shaft 93, however it is also possible to secure this apparatus in front of the mouth 91 at the thread suction apparatus 90. On the side, of the cutting apparatus 92, facing awjy from the mouth 91 there is further located a thread clamp 95 which, in the embodiment shown, is actuated jointly with the cutting apparatus 92 by means of an electromagnet 96.

The thread connection apparatus 97, which has already been mentioned and may, for example, be constructed as a knotting apparatus, is disposed in the path of the thread between the pair of draw-off rollers 13 and the auxiliary pair of draw-off rollers 900. A thread storage apparatus 98 is located between the pair of draw-off rollers 13 and the thread connection apparatus 97. Furthermore, between the thread connection apparatus 97 and the auxiliary pair of draw-off rollers 900 a deflection member 99 is provided which keeps the thread extending to the bobbin 33, together with a suction nozzle 24, to a precisely defined thread path. This suction nozzle 24 may be brought out of a thread takeup position, in which it takes up the thread section extending from the bobbin 33 to the thread clamp 100 95, into the position shown in figure 4.

The apparatus illustrated in figures 3 and 4 operates as follows:

When a thread break occurs, the open-end spinning apparatus in question is stopped, in the manner mentioned with respect to the example of figure 1, and the servicing apparatus 2 is brought into the thread-joining position. The preparation and suction of the thread 3 into the suction tube 20 also occur in the manner described. When a sufficient length of thread has been sucked into the suction tube 20, such that it is ensured that the thread 3 may be retained securely by the suction tube 20, the thread 3 is inserted in the clamping line of the auxiliary pair of draw-off rollers 900 located in the vicinity of the thread path, by means of usual means which are not shown. The thread, which has been further unwound by winding back the bobbin 33, is now taken up by the mouth 91 of the thread suction apparatus 90 located in the vicinity of the thread path between the bobbin 33 and the auxiliary pair of draw-off rollers 900 and sucked up in the form of a loop 37. As soon as a thread length sufficient for thread joining has been sucked into the thread suction apparatus 90, the bobbin 33 is stopped and the thread 38 between the bobbin 33 and the mouth 91 is severed by means of the cutting apparatus 92 and is retained by the thread clamp 95. The suction nozzle 24 is now brought into the region of the thread path between the bobbin 33 4 J a 9 GB 2 115 020 A 9 and the thread clamp 95. The winding back of the 65 bobbin 33 is continued. The thread clamp 95 releases the thread 38, which is now taken up by the suction nozzle 24. When the thread length taken up by the suction nozzle 24 ensures that the thread 38 is reliably held even when the suction nozzle 24 is pivoted, the latter is brought into a position shortly after the pair of draw-off rollers 13-viewed in the direction in which the thread is drawn off out of the thread draw-off tube 12. Subsequently the thread deflection member 99 is pivoted into the path of the thread between the bobbin 33 and the suction nozzle 24, as a result of which the thread 38 is deflected.

Independently thereof the thread 3, which extends from the thread suction apparatus 90 to 80 the suction tube 20 and is inserted in the auxiliary pair of draw-off rollers 900, is taken up by the auxiliary pair of rollers 21, is brought to the length required for thread joining and delivered to the suction tube 12. The auxiliary pair of rollers 21 and the auxiliary pair of draw-off rollers 900 are now rotated back simultaneously and synchronously such that the thread 3 is delivered back into the spinning rotor 11. Subsequently the clamping action of the auxiliary pair of rollers 21 90 is discontinued whereupon this auxiliary pair of rollers 21 may return to its initial position. The clamping action of the auxiliary pair of draw-off rollers 900, whose direction of rotation is now reversed, is, however, maintained. As a result of 95 the reversal of the direction of rotation of this auxiliary pair of draw-off rollers 900 the thread 3 is again drawn off out of the spinning rotor 11.

The thread 3 is, in this connection, delivered to the thread suction apparatus 90 which takes up 100 the spun thread 3.

Just as in the case of the drawing off of the thread join by the bobbin 33, also in this case the thread 3 in the thread joining phase is released 105 over a very great length. The twists in the thread 3 produced by the spinning rotor 11 rotating at full speed may thus be distributed over a great length such that the resistance with respect to the transmission of twist to the collecting surface (collecting groove), which is produced by the deflection of the thread at the mouth, of the thread draw-off tube 12, facing the spinning rotor 11, is sufficient for an essentially longer time in order to prevent excessive twist in the thread section located in the spinning rotor 11. Within certain maximum limits a speed of the spinning rotor 11 which is fast to a greater or lesser extent may be selected in this way according to the size of the distance between the auxiliary pair of draw- 120 off rollers 900 and the thread draw-off tube 12.

The suction nozzle 24 and the deflection member 99 occupy such a position with respect to the path of the thread drawn off by the auxiliary pair of draw-off rollers 900 out of the spinning rotor 11 that the thread section between the suction nozzle 24 and the deflection member 99 extends in an essentially parallel manner to the thread section between the thread draw-off tube 12 and the auxiliary pair of drawoff rollers 900. The bobbin 33 is now stopped.

The thread store 98 is subsequently pivoted into the path of the thread drawn off by the auxiliary pair of draw-off rollers 900 out of the thread draw-off tube 12. The thread connection apparatus 97 is then brought into the path of the threads 3 and 38. While the thread connection process is being carried out both threads 3 and 38 have to be stopped in its operating area. This occurs in that the quantity of thread from the thread store 98 subsequently delivered from the spinning rotor 11 is intermediately stored, whilst the thread 38 is not moved as a result of the stopping of the bobbin 33. During the course of the thread connecting process, the two threads extending to the thread suction apparatus 90 and the suction nozzle 24 are cut off and led away.

After termination of the thread connecting process the thread connection apparatus 97 releases the thread which now extends from the spinning rotor 11 to the bobbin again. The bobbin 33 is lowered onto the main drive roller 31 and again driven thereby, the thread store 98 gradually being emptied again. The deflection member 99 now also releases the thread such that it again assumes its usual path for production.

If the apparatus described with reference to figures 3 and 4 is used without the thread join having to be replaced by another type of thread connection, the cutting apparatus 92 and the thread clamp 95 are not actuated. At the same time as the beginning of the process for drawing off the thread join by means of the auxiliary pair of draw-off rollers 900 or shortly afterwards, the bobbin 33 is again brought to rest on the main drive roller 31 and, in time therewith, the thread is released from the auxiliary pair of draw-off rollers 900 in a manner known per se.

In the case of low operating speeds the drawoff run-up speed may be freely selected; with high thread draw-off speeds, however, for the reasons described above, it is appropriate for the run-up curve to be adapted to the run-up curve, of the fibre supply effective in the spinning rotor 11.

When driving an auxiliary pair of draw-off rollers 900 according to figures 3 and 4, there is no difficulty in adhering to a certain run-up curve, since the masses, of this pair of rollers, to be driven are always constant.

In order to obtain definite slip conditions during the drawing-off of the thread join by the bobbin 33, it is necessary for separate devices to be provided for raising the bobbin 33 from the main drive roller 31 and for driving the bobbin. In principle it is thereby possible for the bobbin raising device 4 to engage at the bobbin arm 32 or at an arm 35 fitted thereon and simultaneously form the support device 8, i.e. the bobbin 33 with its imaginary axis is held in a lifting position during the entire thread break removal process. Also in this case the position of the pivot arm 50 of the auxiliary bobbin drive 5 alters according to the size of the bobbin, such that the tension I 7,T', GB 2 115 020 A 10 spring 7 produces a different contact pressure on the bobbin in dependence upon the diameter of the bobbin. Certainly, in the case of this type of embodiment only the radius of the bobbin 33, i.e. its half diameter, acts upon the tension spring 7.

If a light barrier monitoring device is associated with the bobbin 33, the bobbin 33 may also be raised by means of this monitoring device in such a way that the distance a between the periphery of the bobbin 33 and the periphery of the main drive roller 31 is always the same irrespective of the diameter of the bobbin. In this manner, just as with the embodiment described with reference to figure 1, the entire diameter of the bobbin 33 may be utilized for altering the spring tension. 80 A light barrier monitoring device of this type may also be used when a support device 8 is provided which does not, however, comprise separate drive and support levers.

When a support device 8 is provided with a separate drive and support lever (80 and 81), a switching apparatus is provided which 'is constructed as a switch 85 in the construction illustrated. If desired, instead of the switching apparatus, a shifting lever system may also be provided which causes the drive lever 80 to be uncoupled from the motor 86 and secured (for example by means of a catch) in its temporary position. The stops 82 and 83 also may optionally be disposed on the drive lever 80 or on the support lever 81 or also distributed on both 95 levers.

The support device 8 does not have to be supported on an additional arm 35 of the bobbin arm 32 but may also engage on the latter or on an extension thereof.

The construction of the resilient element associated with the pivot arm 50 may also deviate from the figure. It is certainly possible to provide a hydraulic or pneumatic piston instead of a spring. Instead of a tensionspring 7 a pressure spring may also be used. Figure 2 shows a further variant of the apparatus in which a torsion spring is provided, one leg 71 of which is supported on the pivot arm 50 and the other leg 72 of which is supported on a bearing 54 accommodating the shaft 51 of the pivot arm 50. As figure 2 shows, a construction of this type is particularly compact.

The roller 52 in the construction described has a cover 53 of soft rubber or some other material. As a result of this an enlargement of the 115 contact surface of the roller 52 on the bobbin 33 is achieved, since the cover 53 endeavours to deflect laterally the contact pressure acting thereon. The roller 52 may thus, inspite of good drive entrainment, even comprise a smooth surface, such that the material wound on the bobbin 33 is treated carefully in comparison, for example, to a roller which consists entirely of metal and is provided with a corrugation or the like which, of course, is also possible.

The drive of the various elements-such as the suction tube 20, pivot arm 50 and drive lever 80 or the elements which have been mentioned but not illustrated-may occur in various ways, for example by means of pneumatic or hydraulic pistons. The construction shown with an adjustable intermediate lever system 64, 65, 66, 67, 68 is particularly advantageous if the motor 60 drives various cam discs 62 via the camshaft 6 1, for example for the movement of the suction tube 20 and/or for the pivoting of the auxiliary pair of rollers 21 and/or for raising the pressure roller from the driven roller of the pair of draw-off rollers 13. In this case the intermediate lever system 64, 65, 66, 67, 68 enables the individual drives to be adapted in a particularly simple manner to the operating conditions, in particular when dimensions which are as identical as possible, of the individual parts of this intermediate lever system, are to be provided.

It is further possible to provide another direction of the material flow, wherein the operating elements are to be provided in an arrangement which differs from the drawing and is correspondingly adapted.

Claims

Claims

1. Method for joining a thread in an open-end spinning apparatus, in which the thread is delivered back to the open-end spinning apparatus by winding back a bobbin and an auxiliary pair of rollers and subsequently is again drawn out of the open-end spinning apparatus by a pair of draw-off rollers, characterized in tnat, after termination of the return delivery, the thread is released from the auxiliary pair of rollers and, until the beginning of the normal spinning drawoff process, is subjected to an auxiliary draw-off process at a greater distance from the open-end spinning apparatus than this spinning draw-off process.

2. Method according to claim 1, characterized in that the auxiliary drawoff process occurs exclusively by means of the bobbin.

3. Method according to claim 1, characterized in that the auxiliary drawoff process occurs independently of the bobbin.

4. Method according to one or more of claims ll to 3, characterized in that the auxiiiary draw-off process is maintained in an essentially constant relation to the run-up curve of the fibre infeed which is effective in the open-end spinning apparatus.

5. Method according to one or more of claims 1 to 4, characterized in that before the return delivery of the thread via a throw-off member a reserve thread is formed and the thread end to be delivered to the open- end spinning apparatus is brought to a defined length; in that the return delivery of the thread end by means of the auxiliary pair of rollers only occurs in a readiness position inside the open-end spinning apparatus; and in that after the release of the thread by the auxiliary pair of rollers the return delivery of the thread join occurs by the thread being thrown off by the throw-off member.

6. Method accoring to claim 5, the open-end spinning apparatus comprising a spinning It C 11 GB 2 115 020 A 11 member which may be exchanged for a spinning member with a different diameter, characterized in that the readiness position inside the open- end 65 spinning apparatus is selected such that the path of the return delivery of the thread join by throwing off the thread is always the same size irrespective of the diameter of the spinning member selected in each case.

7. Apparatus for joining a thread in an open- end spinning apparatus, With an auxiliary pair of rollers for taking up, delivering back and releasing the thread at the open-end spinning apparatus, with a pair of draw-off rollers for drawing off the 75 thread during the normal spinning process, for performing the method according to one or more of claims 1 to 6, characterized by an auxiliary draw-off apparatus (33, 900) which is disposed at a greater distance from the open-end spinning 80 apparatus than the pair of draw-off rollers (13).

8. Apparatus according to claim 7, with a bobbin device comprising bobbin arms for taking up a bobbin, with a main drive roller for driving the bobbin and a device for raising the bobbin 85 from the main drive roller and for driving the bobbin, this device comprising a pivot arm and a roller which may be driven in both directions as well as a controllable pivot drive, for the pivot arm, which operates against the action of a resilient element, characterized in that the auxiliary draw-off apparatus is formed by the bobbin device (3), the device for raising and driving the bobbin (33) consisting of a bobbin raising device (4) for forming a defined distance (a) between the bobbin (33) and the main drive roller (3 1) and an auxiliary bobbin drive (5) which may be caused to act on the side, of the bobbin (33), facing away from the main drive roller (3 1) by the action of the resilient element (7, 70).

9. Apparatus according to claim 8, characterized in that the bobbin lifting device (4) comprises a lifting element (40) which cooperates with the side, of the bobbin (33), facing the main drive roller (3 1); and in that a support device (8) which cooperates with a bobbin arm (32) and ensures the defined distance (a) between the peripheral surfaces of the bobbin (33) and the main drive roller (31) is associated with the bobbin lifting device (4).

10. Apparatus according to claim 9, lever (80), may be pivoted between two end positions, is acted upon by a resilient element (84) in the direction towards the bobbin (33) and may thereby be brought into its first end position (82) and, by running up on one of the two bobbin arms (32) may be brought into its second end position (83), with which a switching apparatus (85) for terminating the pivotal movement of the drive lever (80) is associated.

12. Apparatus according to claim 11, characterized in that the controllable drive for the drive lever (80) is constructed as an electric motor (86) and the switching apparatus is constructed as a switch (85) which is arranged on the drive lever (80) and interrupts the supply of current to the motor (86) when actuated.

13. Apparatus according to claim 11 or 12, characterized in that the end positions of the support lever (8 1) are determined by two stops (82, 83) mounted on the drive lever (80).

14. Apparatus according to one or more of claims 8 to 13, characterized in that the resilient element associated with the pivot arm (50) is constructed as a torsion spring (70).

15. Apparatus according to one or more of claims 7 to 14, characterized in that the pivot drive for the pivot arm (50) comprises a rotatable cam disc (62) as well as an adjustable intermediate lever system (64, 65, 66, 67, 68) between the cam disc (62) and the pivot arm (50).

16. Apparatus according to one or more of claims 7 to 15, characterized in that the roller (52) bears a cover (53) consisting of a soft material, preferably soft rubber.

17. Apparatus according to claim 7, characterized in that the auxiliary draw-off device is formed by a second auxiliary pair of draw-off rollers (900) which may be caused to act on the side, of the pair of draw-off rollers (13), facing away from the open-end spinning apparatus.

18. Apparatus according to claim 17, characterized in that between the pair of draw-off rollers (13) and the second auxiliary pair of draw off rollers (900) a thread connection apparatus (97) may be brought into the path of the thread.

19. Apparatus according to one or more of claims 7 to 18, characterized in that a thread cutting apparatus and a return delivery measuring characterized in that, in the case of an open-end apparatus are associated with the auxiliary pair of spinning machine (1) with a plurality of open-end rollers (2 1), and in that a thread throw-off spinning devices, the bobbin lifting device (4) is member (25) which deflects the thread (3) is disposed so as to be stationary for each spinning 115 further arranged between the pair of draw-off station and the support device (8) and the auxiliary bobbin drive (5) are disposed on a servicing apparatus (2) which may be moved along the open-end spinning devices.

11. Apparatus according to one or more of claims 8 to 10, characterized in that the support device (8) comprises a drive lever (80) which may be pivoted by a controllable drive (86) as well as a support lever (81) which is arranged on the drive rollers (13) and the bobbin (33).

20. Apparatus according to claim 19, with a spinning member which may be exchanged for a spinning member with a different diameter, characterized in that the return delivery measuring apparatus may be set in dependence upon the diameter of the spinning member selected in each case.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1983. Published by the Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained